Crude oil is a mixture of many liquids. The crude oil enters the bottom of a tall column, where the mixture is heated. The substances rise up the column until they cool down and condense back to liquids.

The components of crude oil can be separated because of differences in which property?
A/density
B/magnetism
C/boiling point
D/physical state

Fractional distillation is a process that is often employed to separate various liquids from a mixture of liquids based on the respective boiling points. As the liquid mixture is heated, the component with the lowest boiling point will vaporize first and can be separated out through a condenser.

Crude oil is a mixture of several volatile hydrocarbons each having a different boiling point. Therefore, the difference in boiling point can be used to separate them through the method of fractional distillation